• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.771-781
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• 1994

Monthly measurements made at 15 stations along the axis of the upper Neuse River estuary show a highly variable degree of correlation between concentration of suspended particulate material (SPM) and attenuation coefficient (c) of light as measured by transmissometer. Coefficients of determination along transect lines ranged from $0.12{\sim}0.93$ and calibration slopes ranged from $0.50{\sim}5.63$. When examined on a station-by-station basis, coefficients of determination ranged from $0.21{\sim}0.96$ and calibration slopes ranged from $1.04{\sim}4.94$. Surface calibrations made at individual stations over the full 13-month period were the most consistent of all observations and were considerably better than calibrations made using all of the stations on a given day. Organic content, which can dominate the suspended sediment load during some months, does not appear to explain the variations in reliability of the calibrations. However, an abundance of large aggregates with time-varying size and shape distributions may be partly responsible for variations in optical properties of the sediments, and thus may confound the relationship between SPM and c in the Neuse River estuary Time-varying calibrations to account for non-negligible changes in optical properties may not suffice in complex estuarine environments where the in situ particle dynamics are poorly understood. However, the best use of Beam Transmissometer will continue to be for applications such as detecting water-column events or for use in situations where wide error bars in establishing SPM concentrations are acceptable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.112-118
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• 2018

In order to meet the strict emission regulations for internal combustion engines based on fossil fuel, the proportion of after-treatments for vehicles and vessels is gradually increasing. Diesel engines have high power, good fuel economy, and lower $CO_2$ emissions, and their market shares are increasing in commercial vehicles and passenger cars. However, NOx is generated in the localized high-temperature combustion regions, and particulate matter is formed in the zones of diffusion combustion. LNT and urea-SCR catalysts have been developed for after-treatment of the exhaust gas to reduce NOx in diesel vehicles. This study aims to improve the NOx reduction performance of Cu SCR catalyst, which is widely used in light, medium, and heavy-duty diesel engines. The de-NOx performance of $5Cu-2ZrO_2$/93Zeolyst(Si/Al=13.7) SCR catalyst was about 5-50% higher than that of $5Cu-2ZrO_2$/93Zeolite(Si/Al=2.9) at catalyst temperatures of $300^{\circ}C$ or higher. The zeolite had lower metal dispersion than zeolyst, and the reaction rate of the catalyst decreased as the average particle size increased. The $10Cu-2ZrO_2$/88Zeolyst catalyst loaded with 10wt% Cu had the highest NOx conversion rate of 40% at $200^{\circ}C$ and about 65% at $350^{\circ}C$. The ion exchange rate of Cu ions increased with that of Al, the crystalline compound of zeolite, and the de-NOx performance was improved by 20-40% compared to other catalysts.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.613-619
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• 2006

The objectives of this research are to evaluate the effect of membrane materials, particulate matter and membrane pore size on permeate flux. It was shown that the removal efficiency of high MW organic matter more than 10 kDa was lower than that of low MW organic matter for $MIEX^{(R)}$ process. For the change of permeate flux by the pretreatment process, $MIEX^{(R)}+UF$ process showed high removal efficiency of organic matter as compared with coagulation+UF processes, but high reduction rate of permeate flux was presented through the reduction of removal efficiency of high MW organic matter. The pretreatment of the raw water significantly reduced the fouling of the hydrophilic membrane, but did not decrease the flux reduction of the hydrophobic membrane. Flux decline on MF process increased due to the pore clogging, while the permeate flux decline of UF process decreased due to the formation of cake layer. It was shown that particle matter was not effect on MIEX+membrane process. But, for coagulation+membrane process, particle matter was important factor on permeate flux.

• Journal of Wetlands Research
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• v.18 no.2
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• pp.194-200
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• 2016

The impervious surface rate increased by urbanization causes various problems on the environment such as water cycle distortion, heat island effect, and non-point pollutant discharges. The Low Impact Development (LID) techniques are significantly considered as an important tool for stormwater management in urban areas and development projects. The main mechanisms of LID technologies are hydrological and environmental pollution reduction among soils, media, microorganisms, and plants. Especially, the media provides important functions on permeability and retention rate of stormwater runoff in LID facilities. Therefore, this research was performed to assess the pollutant removal efficiency for different types of media such as zeolite, wood chip, bottom ash, and bio-ceramic. All media show high pollutant removal efficiency of more than 60% for particulate materials and heavy metals. Double layered media is more effective in reducing heavy metals by providing diverse sizes of micro-pores and macro-pores compared to the single layered media. The results recommend the use of different sizes of media application is more cost-effective in LID than a single size of media. Furthermore, soluble proportion of total heavy metal in the stormwater is an important component in proper media selection and arrangement.

• Journal of fish pathology
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• v.9 no.1
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• pp.1-9
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• 1996

Many encysted metacercariae of Clinostomum complanatum(Rudolphi, 1814) were found in the flesh near the skin of goldfish(Carassius auratus) sultured at a fish farm in Chonbuk Province, Korea, in the summer of 1995. The mortality reached about 7% from July 10 to August 20. Encysted and excysted metacercariae were$700\sim877{\times}700\sim775{\mu}m$ and $2.4\sim5.5{\times}0.7\sim1.37{\mu}m$ in size, respectively. The parasites looked yellowish due to the yellow particulate matter in the intestine. Of 276 fish examined, 234(84.8%) were infected with a mean intensity of 216.6(range 1~1.214) parasites. Fish of 2.0~2.5 cm in body length were most frequently(94.3%) infected but those of 3.1~3.5 cm were the least infected(75.27%). The isthmus was most heavily infected. There was no difference in prevalence between two forms of goldfish, Gyariko an Ryugum. The sites of infection were swollen and recognized as yellow spots of 0.4~0.8 mm in diameter. Fish infected with more than 200 metacercariae became moribund with listless swimming and finally died.

• Journal of the Korean Ceramic Society
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• v.40 no.6
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• pp.577-582
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• 2003

BaTiO$_3$ fine powders were synthesized by hydrothermal process from peroxo-coprecipitate precursors. The peroxo-coprecipitates were obtained by addition of the BaCl$_2$, TiCl$_4$, and $H_2O$$_2$ aqueous solution to an ammonium solution. Hydrothermal reaction was conducted at various reaction temperatures, times and pH ranges. Unlike the conventional hydrothermal synthesis which needs highly alkaline condition over pH 13 with KOH or NaOH, the present method offered well-developed crystalline (perovskite) BaTiO$_3$ powders synthesized below pH 12 with use of ammonium solution. It was found that the phase-pure fine powders were formed at temperatures as low as 11$0^{\circ}C$ and the properties of the powders synthesized over 13$0^{\circ}C$ were almost same regardless of the reaction time. BET surface area of the prepared powder was as high as 76 $m^2$/g and the calculated particle (particulate) size was below 20 nm. The ultrafine particulates formed weak agglomerates. The microstructure and dielectric properties of BaTiO$_3$ ceramics sintered at the temperature range of 1150~125$0^{\circ}C$ were evaluated.

• Journal of environmental and Sanitary engineering
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• v.7 no.2
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• pp.95-110
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• 1992

Much progress has been made in understanding the subcellular events of the human lung injuries after acute exposure to environmental air pollutants. Host of those events represent oxidative damages mediated by reactive oxygen species such as superoxide, hydrogen peroxide, and the hydroxy, free radical. Recently, nitric oxide (NO) was found to be endogenously produced by endothelial cells and cells of the reticulo-endothelial system as endothelialderived relaxation factor (EDRF) which is a vasoactive and neurotransmitter substance. Together with superoxide, NO can form another strong oxidant, peroxonitrite. The relative importance of exogenous sources of $N0/N0_2$ and endogenous production of NO by the EDRF producing enzymes in the oxidative stresses to the heman lung has to be elucidated. The exact events leading to chronic irreversible damage are still yet to be known. From chronic exposure to oxidant gases, progressive epithelial and interstitial damages develop. Type I epithelial cells become thicker and cover a smaller average alveolar surface area while thee II cells proliferate instead. Under acute damages, the extent of loss of the alveolar epithelial cell lining, especially type II cells appears to be a good predictor of the ensuing irreversible damage to alveolar compartment. Interstitial matrix undergo remodeling during chronic exposure with increased collagen fibers and interstitial fibroblasts. However, Inany of these changes can be reversed after cessation of exposure. Among chronic lung injuries, genetic damages and repair responses received particular attention in view of the known increased lung cancer risks from exposure to several air pollutants. Heavy metals from foundry emission, automobile traffics, and total suspended particulate, especially polycystic aromatic hydrocarbons have been positively linked with the development of lung cancer. Asbestos in another air pollutant with known risk of lung cancer and mesothelioma, but asbestos fibers are nonauthentic in most bioassays. Studies using the electron spin resonance spin trapping method show that the presence of iron in asbestos accelerates the production of the hydroxy, radical in vitro. Interactions of these reactive oxygen species with particular cellular components and disruption of cell defense mechanisms still await further studies to elucidate the carcinogenic potential of asbestos fibers of different size and chemical composition. The distribution of inhaled pollutants and the magnitude of their eventual effects on the respiratory tract are determined by pollutant-independent physical factors such as anatomy of the respiratory tract and level and pattern of breathing, as well as by pollutant-specific phyco-chemical factors such as the reactivity, solubility, and diffusivity of the foreign gas in mucus, blood and tissue. Many of these individual factors determining dose can be quantified in vitro. However, mathematical models based on these factors should be validated for its integrity by using data from intact human lungs.

• Journal of Periodontal and Implant Science
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• v.26 no.1
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• pp.27-46
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• 1996

The purpose of this study was designed to compare with the effects of 4 different surface active bioceramics on the healing process of alveolar bone defects in dogs. Artificial alveolar bone defects depth 4-6mm, width 3-4mm) were created with # 6 round bur at interproximal areas of maxillary canine, maxillary 2nd premolar, mandibular canine, and mandibular 3rd premolar. porous hydroxyapatite(Interpore $200^R$) , 45S5 bioglass, CJ4/lOC crystalline glass, and JJ crystalline glass were implanted in intrabony defects randomly. Experimental groups were divided into 4 categories according to its implant material. After implantation, all groups were examined postoperatively 4 weeks to 12 weeks. 3 dogs was selected randomly and sacrificed after vascular perfusion with 2.5% glutaraldehyde at every 4 weeks. Tissue blocks with surroundig alveolar bone and soft tissues were removed and immersed in formaldehyde/glutaraldehyde fixative. After 20 weeks decalcification with EDTA and formic acid, sections were made and observed under light microscope and transmission electron microscope. In all experimental groups, the encapsulation of inactive connective tissue was observed around graft particles in 4 weeks. As time elapsed, the thickness of surrounding connective tissue was decreased. Osteoconductive bone growth pattern was seen apparently in all groups. CJ4/lOC crystalline glass showed the most active bone formation until 8 weeks. 45S5 bioglass was, however, the most active in new bone formation at 12 weeks. Though there was difference in resorption rate among grafting materials, the size of graft particles was decreased gradually. 45S5 bioglass was resorbed faster than the others. On the other hand, porous hydroxyapatite was degraded most slowly. Phagocytosed particulate matters was observed in the cytoplasm of multinuclear multinuclear giant cell and macrophage under transmission electron microscope. The results suggested suggested that 45S5 bioglass and CJ4/lOC crystalline glass may have some enhanced reparative potential when compared to porous hydroxapatite in the treatment of periodontal defeds. JJ crystalline glass reguires a further investigation of the safety of its use.

• Asian Journal of Atmospheric Environment
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• v.6 no.4
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• pp.281-287
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• 2012

Aerosol concentrations at the CC-Lag site in the Teshio Experimental Forest increased from winter to spring and sometimes showed extremely high values associated with Kosa and/or forest-fire events. The range and mean of the mass concentrations of aerosol chemical species were as follows: total particulate mass, 1.2-29, 5.0; elemental carbon, 0.061-2.2, 0.43; organic carbon, 0.059-3.5, 0.79; and sulfate, 0.12-6.2, 1.8 ${\mu}g/m^3$. The total masses of the deposited particles on hybrid larch and on bamboo leaves were approximately 35 and 30 ${\mu}g/cm^2$, respectively. The amounts of soil particles on the leaves were 6 ${\mu}g/cm^2$ for the upper part of hybrid larch, 2 ${\mu}g/cm^2$ for the lower part of hybrid larch, and 1 ${\mu}g/cm^2$ for Sasa bamboo leaves. The amounts of deposited black carbon were 2.3 ${\mu}g/cm^2$ for the upper part of hybrid larch, 0.6 ${\mu}g/cm^2$ for the lower part of hybrid larch, and 0.2 ${\mu}g/cm^2$ for Sasa bamboo leaves. Half of the total deposited particular mass was attached on the hybrid larch; however, most of the total deposited mass was adhered on the Sasa bamboo leaves. Regardless of the species, there tend to be more deposited particles on the leaves in the upper part than in the lower part, with only a few meters height difference. Comparing the composition of the deposited particles to that of the atmospheric aerosols without any size cut, the fractions of water-soluble material sulfate and sea salt in the deposited aerosols were about one tenth and one hundredth lower than that in the aerosols, respectively. On the basis of the measured concentration and the deposited amount on leaves, the deposition velocity of black carbon was estimated to be approximately 0.5 cm/s.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.358-368
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• 2011

Responses of plankton populations to nutrient enrichment in mesocosm experiments in Shihwa lake were simulated using FVCOM. Dissoloved oxygen module was added to the FVCOM to simulate impacts of its decreased levels. The ecological model included the major components of the pelagic ecosystem including nutrients, phytoplankton (pico-, nano-, micro-), zooplankton (two groups of protozoa, mesozooplankton), particulate organic matter, dissolved organic matter and bacteria, and was calibrated using trophodynamic data collected from Gyeonggi Bay and Shihwa Lake. The model was able to reproduce major responses of plankton populations to nutrient enrichment, including phytoplankton of different size groups, change of dominance of protozoa from < 20 ${\mu}m$ oligotrichs to scuticociliates, and reponses to bacteria and low levels of dissolved oxygen in water column of the mesocosms.